English (the spoken kind) changes from US to UK to Canada to Oz to Kiwi's.. (here in US, cars have trunks, in UK they have boots, and so on)
in Knitting, it's the same deal!
we all cast on, but some of us Cast off and others bind off.
we all make Open stitches (for lace, for buttonholes), but some of YO and some of us Yarn Forward to create these open stitches.
What's worse is-- while i YO --i also sometimes bring the yarn forward!
(when working a slip stitch pattern, i will sometimes bring the yarn forward (as if to purl) slip a stitch, then bring it back (to knit position) and when writing directions i alway write those instruction out..(because Yarn Forward has 2 meanings!)
SO the answer is:
if the pattern is from UK or Oz or from parts of Canada (or just from a USer who has a UK background!)and has lacey 'holes' or if you are making a button hole or some other hole (to thread a cord through)-- Yarn Forward Means YO.
BUT if you are working a slip stitch pattern, it could mean bring the yarn forward (as if to purl) slip the stitch, then bring yarn back (as if to knit)
Look at the picture of the FO, look at directions (and see what you are knitting (button band? edging?) or is it a slip stitch pattern? (a sock heel? and decide what is meant!
if you can't, post the instructions (a few lines, not the whole pattern) or link to an image.. since there are 2 answers, and its hard to know (with out more info!) which answer is the right one!